Document wDmQeb3OxeDQvaax2y2xNj91D

Heating Ventilating Air Conditioning Guide 1939 AIR MOVEMENT AND DISTRIBUTION Stagnant warm air, no matter how pure, is not stimulating and it detracts to some extent from the quality of air. Experience, and recent field studies by the A.S.H.V.E. Research Laboratory46 place the desirable air movement between 15 and 25 fpm under ordinary room temperatures during the heating season. Objectionable drafts are likely to occur when the velocity of the air current is 40 fpm and the temperature of the air current 2 F or more below the customary winter room temperature. Higher velocities are not objectionable in the summer time when the air Fig. 7. Relation Among Rate of Air Change per Occupant, Moisture Content of Enclosure, and Dry-Bulb Temperature of Incoming Air temperature exceeds 80 F. Variations in air movement and temperature in different parts of occupied rooms are often indicative of relative air distribution. The work of the A.S.H.V.E. Research Laboratory indicates that an air movement between 15 and 25 fpm with a temperature variation of 3 F or less in different parts of a room, 36 in. above floor, insure satis factory distribution. Considerable evidence was obtained in these tests to' show that measurements of carbon dioxide are not essential for the study of air distribution, or for indirect measurements of outdoor air 4`A.S.H.V.E. Research Report No. 1016--Classroom Drafts in Relation to Entering. Air Stream Temperature, by F. C. Houghten, H. H. Trimble, Carl Gutberlet and M. F. Lichtenfels (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 268). , 70 Chapter 3- Physical & Physiological Principles of Air Conditioning Table 4. Relation Between Metabolic Rate and Activity3 Hourly Meta bolic Rate por Avo. Person or Total Heat Dissipated, Btu per Hour Hourly Sensible Heat Dissipated, Btu pee Hour Hourly Latent Heat Dissipated. Btu per Hour Average Person Seated at Rest1 Average Person Standing at Rest 384 431 482 Office Worker Moderately Active 490 Clerk, Moderately Active, Standing at Counter.----- Book Binder1.-- Shoe Maker*; Clerk, Very Active Standing at Counter -- Pool Player. .......------- 600 626 661 680 Walking 2 mph. 4; Light Dancing.. Metal Worker*............................... Painter of Furniture*---------------Restautent Serving, Very Busy. 761 862 ' 876 1000 Walking 3 mph*..`................. -...... 1050 Walking 4 mph*. 4; Active Dancing, Roller Skating......... 1390 Stone Mason*...............-................ Bowling.....:........... ...................... -- Man Sawing Wood*--------------- Slow Run4-- Walking 5 mph*.......................... Very Severe Exercise*........ -..... ' 1490 1500 1800 2290 2330 2560 Maximum Exertion Different People4...... ............................... 3000 to 4800 225 225 225 225 225 225 225 230 250 277 280 325 . 346 452 490 490 590 159 206 257 265 375 401 436 450 . 511 585 596 675 704 938 1000 1010 1210 Moisture Dissipated, per Hour Grains 1070 1390 1740 1790 2530 2710 2940 3040 3450 3950 4020 4560 4750 6330 6750 6820 8170 Lb - 0.153 0.199 0.248 0.256 0.362 0.387 0.420 0.434 0.493 0.564 0.575 0.651 0.679 0.904 0.964 0.974 1.167 Metabolism rates noted based on tests actually determined from the following authoritative sources: `A.S.H.V.E. Research Laboratory; `Becker and Hamalainen; 'Douglas, Haldane. Henderson and Schneider; Henderson and Haggard; and `Benedict and Carpenter. Metabolic rate9 for other activities estimated. Total heat dissipation integrated into latent and sensible rates by actual tests for metabolic rates up to 1250 Btu per hour, and extrapolated above this rate. Values for total heat dissipation apply for all atmos pheric conditions in a temperature range from approximately 60 to 90 F dry-bulb. Division of total heat dissipation rates into sensible and latent heat holds only for conditions having a dry-bulb temperature of 79 F. For lower temperatures, sensible heat dissipation increases and latent heat decreases, while for higher temperatures the reverse is true. Table 5. Degrees of Perspiration for Persons Seated at Rest Under Various Atmospheric Conditions Degree or Perspirations Forehead clammy___ Body clammy______ Body damp................ Beads on forehead__ Body wet.. Perspiration on forehead runs and drips___ Perspiration runs down body____ ! Atmospheric Condition 95 Per Cent Relative Humidity 20 Per Cent Relative Humidity E. T. 73.0 73.0 79.0 80.0 84.5 88.0 88.5 D. B. 73.6 73.6 79.7 80.8 85.4 89.0 89.5 W. B. 72.4 72.4 78.4 79.4 84.0 87.6 88.1 E.T. 75.0 75.0 81.0 8710 86.5 94.0 90.0 D. B 87.0 87.0 97.5 109.4 108.5 125.2 116.0 W. B. 60.7 60.7 67.5 75.2 74.6 85.4 79.5 Forty per cent of subjects registered degree of perspiration equal to or greater than indicated. 71 *1